|
Interpreting the infrared
spectrum of methoxymethane
(dimethyl ether)
Doc
Brown's Chemistry Advanced Level Pre-University Chemistry Revision Study
Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students US
K12 grade 11 grade 12 organic chemistry courses involving molecular
spectroscopy analysing infrared spectra of methoxymethane
email doc
brown
Use your
mobile phone or ipad etc. in 'landscape' mode
This is a BIG
website, you need to take time to explore it
Infrared spectroscopy - spectra index
Spectra obtained from a liquid film of methoxymethane. The right-hand part of the of the
infrared spectrum of methoxymethane, wavenumbers
~1500 to 400
cm-1 is considered the fingerprint region for the
identification of methoxymethane and most organic compounds. It is due to a unique set
of complex overlapping vibrations of the atoms of the molecule of
methoxymethane.
Methoxymethane (dimethyl ether)
Revision notes on the structure and naming
(nomenclature) of aliphatic ALCOHOLS and ETHERS
Interpretation of
the infrared spectrum of methoxymethane
The most prominent infrared absorption lines of
methoxymethane
The C-H stretching vibrations for a O-CH3
group occur at wavenumbers 2830 to 2815 cm-1.
The C-O stretching vibrations for a CH2-O-CH2
grouping occur at wavenumbers 1150 to 1060 cm-1.
The absence of other specific functional group bands
will show that a particular functional group is absent from the
methoxymethane
molecular
structure.
See also comparing the IR, mass,
1H NMR and
13C NMR spectra of
isomers of C2H6O
below.
TOP OF PAGE
|
Comparing the infrared, mass, 1H NMR and 13C NMR
spectra of the 2 isomers of C2H6O
NOTE: The images are linked to their
original detailed spectral analysis pages AND can be doubled in
size with touch screens to
increase the definition to the original ethanol (ethyl
alcohol) and
methoxymethane (dimethyl ether) image sizes. |
 |
 |
|
INFRARED SPECTRA:
Apart from the significant differences in the fingerprint region at
wavenumbers 1500 to 400 cm-1, the most striking
difference is the broad O-H stretching band ~3400 cm-1,
found in the infrared spectrum of alcohols, but absent in
the infrared spectrum of ethers. You can clearly see, in the
infrared spectrum of methoxymethane, the complete absence of the
O-H vibration absorption band. |
 |
 |
|
MASS SPECTRA: Both
ethanol and methoxymethane show some similarities in their mass
spectra, but their base ion peaks are quite different - for ethanol
it is m/z 31 and for methoxymethane it is m/z 45. |
 |
 |
|
1H NMR SPECTRA: The 1H NMR spectra of
ethanol and methoxymethane are quite significantly different.
Ethanol gives 3 peaks in the proton ratio 3:2:1 (3 different
chemical environments), whereas methoxymethane only gives one
1H chemical shift peak (all 6 protons in the same
chemical environment). |
 |
 |
|
13C NMR SPECTRA: The 13C NMR spectra of
ethanol and methoxymethane are different. Ethanol gives two
13C resonances, but methoxymethane only one (2
different 13C chemical environments and a 13C
single chemical environment). |
Key words & phrases: C2H6O CH3OCH3 image and diagram explaining the infrared spectrum
of methoxymethane, complete infrared absorption spectrum of methoxymethane, comparative spectra of
methoxymethane, prominent peaks/troughs for identifying functional groups in the infrared spectrum of
methoxymethane,
important wavenumber values in cm-1 for peaks/troughs in the infrared spectrum
of methoxymethane, revision of infrared spectroscopy of methoxymethane, fingerprint region analysis of
methoxymethane, how to identify methoxymethane from its infrared spectrum, identifying organic
compounds like methoxymethane from their infrared spectrum,
how to analyse the absorption bands in the infrared spectrum of methoxymethane detection of functional groups in the
methoxymethane molecule example of the infrared spectrum of a
molecule like methoxymethane with a functional group
interpreting interpretation of the infrared spectrum of methoxymethane shows presence
of functional group
dimethyl ether
Links associated with methoxymethane
Infrared spectroscopy index
ALL SPECTROSCOPY INDEXES
All Advanced Organic
Chemistry Notes
Use My Google search site box
Email doc b:
chem55555@hotmail.com
|
